The invention relates to an inductive distance sensor.
One such distance sensor is known from DE 1 03 28 122 A1.
The core-fitted coil of an inductive distance sensor such as this is fed with a medium frequency from an oscillating circuit, which causes eddy-current losses in the ferromagnetic environment. This leads to the amplitude and phase of the feed frequency being influenced when the ferromagnetic mass changes as a result of moving toward or away from a ferromagnetic object, such as a wing of a door which is fitted locally with iron. A distance sensor such as this can therefore be used not only as a limit switch but also as a high-resolution distance measurement device. However, time-consuming inductive adjustment, which is susceptible to errors, is required for such use as a measurement system.
In order to restrict such adjustment, which is potentially subject to errors, and measurement errors caused in this way, provision is made essentially in the abovementioned prior publication for the inner wall diameter, which is larger than the core, of the winding support to taper resiliently at various circumferential positions on its internal casing surface, as a result of which the core which is introduced therebetween is always centered in the winding support, independently of its cylinder diameter.
However, fine adjustment is normally essential by linear or helical axial movement and final fixing of the core in the winding support. In this case, it is disadvantageous for series production that, in the case of a coil which is arranged in a ferromagnetic pot, the adjustment is achieved, despite the same coil characteristic data, only at axial positions of the core in its winding support which differ from one coil to another.